Minoa building biodigester to turn human waste into electricity

David Lassman/The Post-StandardA working model of a biodigester, or anerobic digester, in a greenhouse at SUNY College of Environmental Science and Forestry will be scaled up for use by the village of Minoa. Working with the model, from left, are Gary Bonomo, graduate student in chemestry at SUNY ESF, assistant professor Klaus Doelle, professor Dave Johnson and Steve Giarrusso, biologist & chief operator of the village's wastewater treatment facility.

Minoa, NY - Minoa is about to build its own small-scale biodigester that will turn food waste and sewage into electricity. And the waste leftover will be converted into fertilizer.

The village, along with the State University College of Environmental Science and Forestry, has been working on a prototype biodigester for months. After rigorous testing and many revisions, the researchers are ready to build a larger version — twice the size of the prototype — at the village’s wastewater treatment plant this summer.

Later, they hope to build a full-size biodigester, which would cost less than $200,000, officials said. The village is hoping to secure grants for that project.

“This is very exciting for us,” said Minoa Village Mayor Richard Donovan.

Although the technology used in the biodigester and other projects in Minoa isn’t new, the assembly of technology in this combination is unique, ESF’s said Dave Johnson, an ESF chemistry professor.

The idea behind the biodigester is to produce methane, which is then converted into electricity, allowing part of the treatment plant and DPW to be taken off the grid. Johnson, who’s been working on the project, said the project could save 25 percent or more of the monthly utility cost.

Eventually, the village wants to cut its utility bill for the wastewater treatment plant and Department of Public Works, Donovan said. It also would save money by using biosolids instead of paying $70 a ton to get rid of them.

“The goal is to be sustainable, and as budgets everywhere get cut, the idea to trim expenses and this is an innovative way of doing it,” said Steve Giarrusso, a biologist and Minoa’s treatment plant superintendent. “Because we’re small and have the full support of the village, we can try out these projects.”

The anaerobic biodigester works using a process where microorganisms break down organic material in the absence of oxygen, producing a biogas composed of methane and carbon dioxide, Johnson said.

When manure and food waste are processed, the gas is captured and burned to generate electricity. The heat from the electric generators is used to heat the biodigester to heat the materials, kill pathogens and speed up the processing time.

The Minoa system will take food waste from village residents and the East Syracuse Minoa school district and mix it with sewage (human waste) to produce what almost looks like broccoli soup. The sewage biocells are used to dilute the food waste, and that’s called codigestion.

The makeshift biodigester built by the researches resembles a handmade contraption, and for the most part it is. The reactor, which is 7 feet long and 18 inches in diameter, is made from a road culvert. The material stays in the first reactor one to three days and then it goes into the second reactor, which is seven times larger than the first one.

In that reactor, the substance “cooks” for 21 days, and during that process makes methane gas. Traces of other gases are then removed from the methane.

The clean methane produced can be run in a compressor.

Donovan said being more sustainable reduces the burden on taxpayers.

“Our ultimate goal here in Minoa is to be an educational and research facility helping other municipalities control their costs by using “green’ systems like this,” he said.